I am thinking that stocking your yard with Native Florida amphipians is not a good idea. First, by purchasing such animals you are encouraging the pet trade in wild species, which should not be supported under any circumstances. Second, you don't know where those animals came from; they might represent subspecies different from those native to your area and releasing them into the wild would contaminate the gene pool of any remaining native animals. Third, you can't be sure they don't carry any diseases that could be spread to wild animals. And fourth, there is probably a law against trading in Native Florida animals like that. Perhaps you should contact the folks here and ask what they suggest -- http://ufwildlife.ifas.ufl.edu/toads.shtml
I would be interested to know what their suggestions are...